EP1380103A2 - Regelung für gesättigte systeme - Google Patents
Regelung für gesättigte systemeInfo
- Publication number
- EP1380103A2 EP1380103A2 EP02726214A EP02726214A EP1380103A2 EP 1380103 A2 EP1380103 A2 EP 1380103A2 EP 02726214 A EP02726214 A EP 02726214A EP 02726214 A EP02726214 A EP 02726214A EP 1380103 A2 EP1380103 A2 EP 1380103A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- power amplifier
- loop
- power
- gain
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 229920006395 saturated elastomer Polymers 0.000 title description 2
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000004891 communication Methods 0.000 claims description 8
- 230000001413 cellular effect Effects 0.000 claims description 5
- 238000012546 transfer Methods 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 230000033772 system development Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3036—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers
Definitions
- the present invention relates generally to the field of power amplifiers; and more particularly, to a method and apparatus for controlling a power amplifier in a cellular telephone utilized in a wireless digital communications system.
- Cellular telephones used in wireless digital communications systems for example, communications systems which operate in accordance with GSM (Global System for Mobile Communications) specifications, contain a power amplifier system to control output power when the telephone is in the transmit mode.
- the output power is typically controlled by regulating the current, which is proportional to the output power, although other parameters proportional to the output power can also be regulated, if desired.
- the power amplifier transfer function gain is not constant.
- the gain can change by as much as a factor of 5 during normal operation. This change in the gain causes the bandwidth of the loop to also change by the same amount.
- Fig. 1 is a graph schematically illustrating power amplifier transfer function gain; i.e., the control signal (Vcon) to current consumption (or output power), for the prior art system.
- the curve 10 in Fig. 1 clearly shows that at very low output power levels 12 and at high power levels 14, the output power essentially does not change with increase in Vcon.
- the cause of the above-described problem is that the control signal into the power amplifier rises or falls with a rise and fall time that is completely determined by how the error amplifier is designed. Because the loop is not locked, the delay caused by the very low gain will change too much if either the supply voltage or the temperature changes.
- the present invention provides a power amplifier system and a method for controlling a power amplifier in a power amplifier system.
- a method according to the present invention controls a power amplifier in a power amplifier system which includes a loop by which a parameter proportional to output power of the power amplifier is sensed and fed back to an error amplifier, and the output of the error amplifier is fed to a control input of the power amplifier as a control signal, the method comprising adding an extra gain to the loop.
- the present invention thus provides an effective, yet relatively simple way, to obtain more robust power regulation.
- the extra gain is proportional to the control signal; and, in an implementation of the invention, the parameter proportional to the output power comprises current.
- a control circuit of the system adjusts the gain of the power amplifier and adds an appropriate extra gain to ensure that the loop will always be active.
- the power amplifier system is incorporated in a mobile terminal, for example, a cellular telephone, utilized in a wireless digital communications system, such as in a system operating in accordance with GSM specifications.
- the method and system of the present invention also provides solutions to other problems that are encountered in power amplifier systems, including problems relating to mismatch at the output of the power amplifier.
- Fig. 1 is a graph schematically illustrating power amplifier transfer function gain in a power amplifier system that is known in the prior art
- Figs. 2 and 3 are graphs schematically illustrating a method for adding extra gain in a power amplifier system according to a presently preferred embodiment of the present invention.
- Fig. 4 illustrates a power amplifier system according to one embodiment of the present invention.
- a power amplifier is controlled by sensing the current to the power amplifier and feeding it back via a loop to an error amplifier, the output of which is fed to a control input of the power amplifier; which, in turn, controls the biasing of the power amplifier.
- the power amplifier transfer function gain is not constant; and this causes the loop to also change. At very low and at high power levels, in particular, there is essentially no gain at all, and any change in the gain that does occur results in an almost infinite relative change in the gain. Because there is no response in the loop feedback, the loop is not working and is inactive.
- Figs. 2 and 3 are graphs of power amplifier transfer function gain illustrating a method according to the present invention.
- Fig. 2 illustrates the gain curve 10 shown in Fig. 1 ; and an extra gain curve 20 to be added to the curve 10 according to a presently preferred embodiment of the present invention.
- Fig. 3 illustrates the resulting curve 25 after adding the extra gain curve 20 to the curve 10.
- the curve 25 in Fig. 3 by adding the extra gain, the overall gain will never be at zero, and there will always be some gain, even at very low output power levels as shown at 27 and at high output power levels as shown at 29.
- the loop will always be active; and because the loop is always locked, there will no longer be any problems with delay.
- Fig. 4 illustrates a power amplifier system according to an embodiment of the present invention for providing the extra gain.
- the system is generally designated by reference number 30, and in this embodiment, the system is incorporated in a cellular telephone, illustrated by dashed box 32, utilized, for example, in a GSM wireless communications system; to control output power when the telephone is in the transmit mode.
- System 30 includes a power amplifier 34 which receives a first RF signal, having a first power level, at an input 36; and which outputs a second RF signal, having a second power level, at output 38.
- the difference between the first and second power levels, i.e., the gain of the power amplifier, is controlled by a control signal which is input to the power amplifier at control signal input 42.
- the second, amplified RF signal is transmitted by the telephone via an antenna 44.
- the control signal at control signal input 42 is provided by sensing the input current to the power amplifier and feeding it to an error amplifier.
- the output signal from the error amplifier is fed to the control signal input 42 of the power amplifier 34.
- the control circuit as so far described is known in the prior art; and will provide a power amplifier transfer function gain in the general form illustrated in Fig. 1.
- the power amplifier system 30 further includes additional circuitry for adding extra gain to the loop which is proportional to the control signal. As a result of this extra gain, the feedback loop will always be active, as shown in Fig. 3, and there will be no further problem with the delay because the loop will always be locked.
- Fig. 4 illustrates only one possible implementation for adding the extra gain to the loop. Other implementations will be readily apparent to those skilled in the art.
- the present invention also provides a solution to mismatch at the output of the power amplifier. Specifically, if a big enough VSWR (Voltage Standing Wave Ratio) at the antenna has a certain phase; the power amplifier will be presented with an increased load impedance. This results in the power amplifier going into saturation earlier. When the down ramping should occur, we would get a delay without adding the extra gain according to the present invention.
- VSWR Voltage Standing Wave Ratio
Landscapes
- Transmitters (AREA)
- Amplifiers (AREA)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US839462 | 1977-10-04 | ||
| US09/839,462 US20020155817A1 (en) | 2001-04-20 | 2001-04-20 | Regulation for saturated systems |
| PCT/EP2002/003406 WO2002087079A2 (en) | 2001-04-20 | 2002-03-27 | Regulation for saturated systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP1380103A2 true EP1380103A2 (de) | 2004-01-14 |
Family
ID=25279787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP02726214A Withdrawn EP1380103A2 (de) | 2001-04-20 | 2002-03-27 | Regelung für gesättigte systeme |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US20020155817A1 (de) |
| EP (1) | EP1380103A2 (de) |
| WO (1) | WO2002087079A2 (de) |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI87028C (fi) * | 1989-12-22 | 1992-11-10 | Nokia Mobile Phones Ltd | Metod foer att reglera effekt hos en spaenningsstyrd effektfoerstaerkare och koppling foer anvaendning i metoden |
| JPH08501197A (ja) * | 1993-03-26 | 1996-02-06 | クァルコム・インコーポレーテッド | 電力増幅器バイアス制御回路および方法 |
| GB2279779B (en) * | 1993-06-02 | 1997-03-05 | Vtech Communications Ltd | Amplifier power control system |
| US5412341A (en) * | 1993-10-28 | 1995-05-02 | Motorola, Inc. | Power control apparatus and method for a radio frequency amplifier |
| GB2306814B (en) * | 1995-11-01 | 2000-03-15 | Roke Manor Research | Improvements in or relating to rf power amplifiers |
| JPH09238037A (ja) * | 1996-03-01 | 1997-09-09 | Nec Corp | 出力電力制御回路 |
| US5898912A (en) * | 1996-07-01 | 1999-04-27 | Motorola, Inc. | Direct current (DC) offset compensation method and apparatus |
| US6025754A (en) * | 1997-11-03 | 2000-02-15 | Harris Corporation | Envelope modulated amplifier bias control and method |
| US6370364B1 (en) * | 1999-06-22 | 2002-04-09 | Nokia Mobile Phones, Ltd. | Mobile station having power control loop offset alignment without requiring RF power measurement |
-
2001
- 2001-04-20 US US09/839,462 patent/US20020155817A1/en not_active Abandoned
-
2002
- 2002-03-27 WO PCT/EP2002/003406 patent/WO2002087079A2/en not_active Ceased
- 2002-03-27 EP EP02726214A patent/EP1380103A2/de not_active Withdrawn
Non-Patent Citations (1)
| Title |
|---|
| See references of WO02087079A2 * |
Also Published As
| Publication number | Publication date |
|---|---|
| US20020155817A1 (en) | 2002-10-24 |
| WO2002087079A2 (en) | 2002-10-31 |
| WO2002087079A3 (en) | 2002-12-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| 17P | Request for examination filed |
Effective date: 20030917 |
|
| AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
| AX | Request for extension of the european patent |
Extension state: AL LT LV MK RO SI |
|
| RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: TELEFONAKTIEBOLAGET LM ERICSSON (PUBL) |
|
| RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: FARZONE, TAGI Inventor name: BRANDT, PER-OLOF |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| 18D | Application deemed to be withdrawn |
Effective date: 20060919 |